Brake check failed

What does 28 mean?

This warning/alarm indicates that a brake check procedure has failed, suggesting that the brake resistor is either not connected to the frequency converter or is not functioning correctly. This condition prevents the drive from effectively controlling the mechanical brake, which can be critical for safety and operational integrity in certain applications.

• Brake resistor not connected to the frequency converter's brake terminals (e.g., 81, 82).
• Open circuit in the wiring between the frequency converter and the brake resistor (e.g., broken cable, loose terminal).
• Brake resistor itself has an open circuit (e.g., internal element broken, corrosion of connections).
• Brake resistor resistance value is significantly out of range (e.g., too high or too low) from parameter 2-11 Brake Resistor Ohm.
• Faulty brake chopper sensing circuit within the frequency converter.

Click steps to track your progress.

1. 1

   Disconnect main power supply to the frequency converter at the upstream breaker. Verify zero voltage at L1, L2, L3 terminals.

2. 2

   Verify the brake resistor cables are correctly and securely connected to the frequency converter's brake terminals (e.g., 81, 82).

3. 3

   Measure the resistance of the brake resistor directly at its terminals using a multimeter. Compare to specified ohmic value (e.g., 22 Ohms).

4. 4

   Measure continuity of the brake resistor cables from the frequency converter terminals to the resistor terminals.

5. 5

   Check parameter 2-11 Brake Resistor Ohm for correct setting matching the installed resistor's specifications.

6. 6

   If the brake resistor is open circuit, replace the resistor unit.